Combining power from electrically isolated power paths for powering remote units in a distributed antenna system(s) (DASs)

ABSTRACT

Embodiments disclosed herein include combining power from isolated power paths for powering remote units in distributed antenna systems (DASs). In one example, a remote unit(s) is configured to include multiple input power ports for receiving power from multiple power paths. The received power from each input power port is combined to provide a combined output power for powering the remote unit. Thus, a remote unit can be powered by the combined output power. To avoid differences in received power on the multiple input power ports causing a power supply to supply higher power than designed or regulated, the input power ports in the remote unit are electrically isolated from each other. Further, the received power on the multiple power inputs ports can be controlled to be proportionally provided to the combined output power according to the maximum power supplying capabilities of the respective power supplies.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/961,098, filed Dec. 7, 2015, which claims the benefit of priorityunder 35 U.S.C. §119 of U.S. Provisional Application No. 62/139,137filed on Mar. 27, 2015, the content of both are relied upon andincorporated herein by reference in their entireties.

BACKGROUND

The technology of the present disclosure relates generally to combiningpower from electrically isolated power paths for powering remote unitsin distributed antenna systems (DASs).

Wireless communication is rapidly growing, with ever-increasing demandsfor high-speed mobile data communication. As an example, local areawireless services (e.g., so-called “wireless fidelity” or “WiFi”systems) and wide area wireless services are being deployed in manydifferent types of areas (e.g., coffee shops, airports, libraries,etc.). Distributed communications or antenna systems communicate withwireless devices called “clients,” “client devices,” or “wireless clientdevices,” which must reside within the wireless range or “cell coveragearea” in order to communicate with an access point device. Distributedantenna systems are particularly useful to be deployed inside buildingsor other indoor environments where client devices may not otherwise beable to effectively receive radio-frequency (RF) signals from a source,such as a base station for example. Example applications wheredistributed antenna systems can be used to provide or enhance coveragefor wireless services include public safety, cellular telephony,wireless local access networks (LANs), location tracking, and medicaltelemetry inside buildings and over campuses.

One approach to deploying a distributed antenna system involves the useof RF antenna coverage areas, also referred to as “antenna coverageareas.” Antenna coverage areas can be formed by remotely distributedantenna units, also referred to as remote units (RUs). The remote unitseach contain or are configured to couple to one or more antennasconfigured to support the desired frequency(ies) or polarization toprovide the antenna coverage areas. Antenna coverage areas can have aradius in the range from a few meters up to twenty meters as an example.Combining a number of remote units creates an array of antenna coverageareas. Because the antenna coverage areas each cover small areas, theretypically may be only a few users (clients) per antenna coverage area.This arrangement generates a uniform high quality signal enabling highthroughput supporting the required capacity for the wireless systemusers.

As an example, FIG. 1 illustrates distribution of communicationsservices to coverage areas 100(1)-100(N) of a DAS 102, wherein ‘N’ isthe number of coverage areas. These communications services can includecellular services, wireless services such as RFID tracking, WirelessFidelity (WiFi), local area network (LAN), WLAN, and combinationsthereof, as examples. The coverage areas 100(1)-100(N) may be remotelylocated. In this regard, the remote coverage areas 100(1)-100(N) arecreated by and centered on remote units 104(1)-104(N) connected to acentral unit 106 (e.g., a head-end controller or head-end unit). Thecentral unit 106 may be communicatively coupled to a base station 108.If the DAS 102 is a broadband DAS, the central unit 106 receivesdownlink communications signals 110D in multiple frequency bands fordifferent communications services from the base station 108 to bedistributed to the remote units 104(1)-104(N). The remote units104(1)-104(N) are configured to receive downlink communications signals110D from the central unit 106 over a communications medium 112 to bedistributed as downlink communications signals 110D to the respectivecoverage areas 100(1)-100(N) of the remote units 104(1)-104(N). Eachremote unit 104(1)-104(N) may include an RF transmitter/receiver (notshown) and a respective antenna 114(1)-114(N) operably connected to theRF transmitter/receiver to wirelessly distribute the communicationsservices to client devices 116 within their respective coverage areas100(1)-100(N). The remote units 104(1)-104(N) are also configured toreceive uplink communications signals 110U in multiple frequency bandsover antennas 114(1)-114(N) from the client devices 116 in theirrespective coverage areas 100(1)-100(N) to be distributed over thecommunications medium 112 to the central unit 106.

Power is provided from one or more power sources to the remote units104(1)-104(N) in the DAS 102 to provide power for the power-consumingcomponents in the remote units 104(1)-104(N). For example, the remoteunits 104(1)-104(N) may receive power P over long wire electricalconductor pairs 118 (“wire pair 118”) provided in the communicationsmedium 112 from one or more power sources 120 (“power source 120”). Forexample, the power source 130 may be remote to the remote units104(1)-104(N) and provided at the central unit 106 or other location inthe DAS 102. The power source 120 may be either an alternative current(AC) or direct current (DC) power supply. Each wire pair 118 may carry alimited amount of current or voltage, which may be dictated by safetyregulations or by physical properties of the wire pairs 118, such astheir diameter and length. However, in some cases, one or more of theremote units 104(1)-104(N) may require more power than can be carried bya single wire pair 118. For example, NEC (National Electrical Code)Class 2 directives may limit the power that can be provided by a singlepower supply to 100 VA (Volt-Ampere).

One solution to deliver more power to the remote units 104(1)-104(N) isto connect multiple wire pairs 118 from multiple power output ports122(1)-122(X) to each remote unit 104(1)-104(N). In this arrangement,each wire pair 118 provides power up to its limited power level.However, the power provided by all wire pairs 118 can be combined inparallel to provide a greater combined power to a remote unit104(1)-104(N). However, the voltages at the end of each wire pair 118may be different due to different voltage drop on the wires, differencesin the adjustment of the power supply 120, and/or differences incomponents' tolerances in the power output ports 122(1)-122(X) of thepower supply 120. If the voltages at the end of each wire pair 118 arenot equal, this will cause the power supply 120 to distribute differentcurrent and thus different power P on power output ports 122(1)-122(X)to a remote unit 104(1)-104(N). In such case, some power output ports122(1)-122(X) will deliver lower power while the other power outputports 122(1)-122(X) will deliver higher power. If power P pulled by thepower supply 120 reaches the limit allowed by safety regulations orcapabilities for a given power output port(s) 122(1)-122(X), the powersupply 120 may shut down thereby interrupting power P to the remoteunits 104(1)-104(N).

No admission is made that any reference cited herein constitutes priorart. Applicant expressly reserves the right to challenge the accuracyand pertinency of any cited documents.

SUMMARY

Embodiments disclosed herein include combining of power fromelectrically isolated power paths for powering remote units indistributed antenna systems (DASs). In this regard, in one example, oneor more remote units in a DAS include multiple input power ports forreceiving power from multiple power paths. Each power path is capable ofdistributing a given maximum power based on its respective power supplyand the power handling capability of the respective power path. Thereceived power from each input power port in a remote unit is combinedto provide a combined output power for powering the remote unit. In thismanner, the remote unit can be powered by the combined output power ifthe remote unit requires more power for operation than can be suppliedover a single power path. To avoid differences in received power on themultiple input power ports causing a power supply from providing higherpower than designed or regulated, the input power ports in the remoteunit are electrically isolated from each other. Further, in someembodiments, to provide for the received power on the multiple powerinputs ports to be proportionally provided in the combined poweraccording to the maximum power supplying capabilities of the respectivepower supplies, a controller is provided. The controller is configuredto selectively control the amount of power provided from each powerinput port to the combined output power, based on the determinedavailable power on each multiple input power port.

By proportionally combining power from electrically isolated power pathsin a remote unit based on the power supplying capability of therespective power supplies, the remote unit can tolerate inaccuracies inthe output power from the power supplies. For example, the type andlength of wires used in the power paths for delivering power to thepower input ports of a remote unit can cause the remote unit to drawpower beyond the limits or regulations of a given power supply. This cansimplify installation procedures for power supplies and remote units ina DAS, because in-field calibrations of power supplies by techniciansbased on variations in power supplies and power paths may be avoided.The remote unit can work with multiple types of power supplies, whichcan have different power delivery capabilities or regulations.

One embodiment of the disclosure relates to a remote unit for adistributed antenna system (DAS). The remote unit comprises a pluralityof internal power paths each configured to carry power to a combinedpower node coupled to at least one remote unit load to provide acombined output power to the at least one remote unit load. The remoteunit also comprises a plurality of input power ports provided in arespective internal power path among the plurality of internal powerpaths, each input power port among the plurality of input power portsconfigured to receive input power from a respective external power pathin a DAS. The remote unit also comprises a plurality of isolationcircuits provided in a respective internal power path among theplurality of internal power paths. Each isolation circuit among theplurality of isolation circuits is configured to receive the input powerfrom the respective input power port and provide an electricallyisolated output power based on the received input power at the combinedpower node to provide the combined output power. The remote unit alsocomprises a plurality of control circuits provided between the combinedpower node and the plurality of isolation circuits in a respectiveinternal power path among the plurality of internal power paths tocontrol the electrically isolated output power provided to the combinedpower node. The remote unit also comprises a controller configured toselectively control the plurality of control circuits to control theelectrically isolated output power delivered from each isolation circuitin the respective internal power path to the combined power node intothe combined output power.

Another embodiment of the disclosure relates to a method of combiningpower received from multiple input ports in a remote unit for a DAS. Themethod comprises receiving input power from a plurality of externalpower paths in a DAS into a plurality of input power ports each providedin a respective internal power path among a plurality of internal powerpaths. The method also comprises providing a plurality of electricallyisolated output powers based on the received input power from arespective input power port among the plurality of input power ports.The method also comprises selectively controlling an amount ofelectrically isolated output power delivered in each respective internalpower path, to a combined power node into a combined output power to beprovided to at least one remote unit load.

Another embodiment of the disclosure relates to a DAS. The DAS comprisesa central unit. The central unit is configured to distribute at leastone downlink communications signal over at least one communicationsmedium to at least one remote unit among a plurality of remote units.The central unit is also configured to receive at least one uplinkcommunications signal over the at least one communications medium fromat least one remote unit among the plurality of remote units. Each ofthe plurality of remote units is configured to receive the at least onedownlink communications signal over the at least one communicationsmedium from the central unit and distribute the received at least onedownlink communications signal from the central unit to at least oneclient device. Each of the plurality of remote units is also configuredto receive the at least one uplink communications signal from the atleast one client device and distribute the received at least one uplinkcommunications signal over the at least one communications medium to thecentral unit. Each of the plurality of remote units further comprises aplurality of internal power paths each configured to carry power to acombined power node coupled to at least one remote unit load to providea combined output power to the at least one remote unit load. Each ofthe plurality of remote units further comprises a plurality of inputpower ports provided in a respective internal power path among theplurality of internal power paths, each input power port among theplurality of input power ports configured to receive input power from arespective external power path in a DAS. Each of the plurality of remoteunits further comprises a plurality of isolation circuits provided in arespective internal power path among the plurality of internal powerpaths. Each isolation circuit among the plurality of isolation circuitsis configured to receive the input power from a respective input powerport and provide an electrically isolated output power based on thereceived input power at the combined power node to provide the combinedoutput power. Each of the plurality of remote units further comprises aplurality of control circuits provided between the combined power nodeand the plurality of isolation circuits in a respective internal powerpath among the plurality of internal power paths. Each of the pluralityof remote units further comprises a controller configured to selectivelycontrol an amount of electrically isolated output power delivered fromthe isolation circuit in the respective internal power path, to thecombined power node into the combined output power.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part, will be readily apparent tothose skilled in the art from the description or recognized bypracticing the embodiments as described in the written description andclaims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understand the natureand character of the claims.

The accompanying drawings are included to provide a furtherunderstanding and are incorporated in and constitute a part of thisspecification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary distributed antenna system(DAS) capable of distributing radio frequency (RF) communicationsservices to client devices;

FIG. 2 is a schematic diagram of an exemplary remote unit that can beprovided in a DAS, wherein the remote unit is configured to combinereceived power from electrically isolated power ports each receivingpower from respective external power paths, for powering the remoteunit;

FIG. 3 is a flowchart illustrating an exemplary process of the remoteunit in FIG. 2 receiving input power from a plurality of external powerpaths into a plurality of input power ports, and selectively controllingthe contribution of power from each of the input power ports to acombined power node;

FIG. 4 is a timing diagram illustrating exemplary duty cycles of controlcircuits in each output power path in the remote unit in FIG. 2controlling the portion of time that power received from a respectiveinput power port is provided to a combined output power;

FIG. 5 is a schematic diagram illustrating more detail of an exemplaryavailable power measurement circuit provided in the remote unit in FIG.2 for measuring the available power from a power supply supplying powerover an external power path to a respective input power port in theremote unit;

FIG. 6A is a flowchart illustrating an exemplary process of measuringthe available power from a respective power supply supplying power overa respective external power path to a respective input power port in theremote unit;

FIG. 6B is a flowchart illustrating an exemplary monitoring process ofthe remote unit in FIG. 2 determining isolation circuit intolerances toperform a correction process to compensate the output power for any suchintolerances;

FIG. 7 is a schematic diagram of another exemplary remote unit that canbe provided in a DAS, wherein the remote unit is configured to combinereceived power from electrically isolated power ports each receivingpower from respective external power paths, to multiple output loads forpowering the remote unit;

FIG. 8 is a schematic diagram of an exemplary DAS employing one or moreremote units configured to combine received power from electricallyisolated power ports each receiving power from respective power paths,for powering the remote unit;

FIG. 9 is a partially schematic cut-away diagram of an exemplarybuilding infrastructure in which a DAS can be employed, wherein one ormore of the remote units is configured to combine received power fromelectrically isolated power ports each receiving power from respectiveexternal power paths, for powering the remote unit; and

FIG. 10 is a schematic diagram of a generalized representation of anexemplary controller that can be included in a remote unit for measuringthe available power from a power supply supplying power over arespective external power path to a respective input power port in theremote unit and/or proportionally controlling the contribution of powerfrom each of the input power ports to the combined output power based onthe measured available power from the respective power supplies, whereinthe exemplary computer system is adapted to execute instructions from anexemplary computer readable medium.

DETAILED DESCRIPTION

Various embodiments will be further clarified by the following examples.

Embodiments disclosed herein include combining of power fromelectrically isolated power paths for powering remote units indistributed antenna systems (DASs). In this regard, in one example, oneor more remote units in a DAS include multiple input power ports forreceiving power from multiple power paths. Each power path is capable ofdistributing a given maximum power based on its respective power supplyand the power handling capability of the respective power path. Thereceived power from each input power port in a remote unit is combinedto provide a combined output power for powering the remote unit. In thismanner, the remote unit can be powered by the combined output power ifthe remote unit requires more power for operation than can be suppliedover a single power path. To avoid differences in received power on themultiple input power ports causing a power supply from providing higherpower than designed or regulated, the input power ports in the remoteunit are electrically isolated from each other. Further, in someembodiments, to provide for the received power on the multiple powerinputs ports to be proportionally provided in the combined output poweraccording to the maximum power supplying capabilities of the respectivepower supplies, a controller is provided. The controller is configuredto selectively control the amount of power provided from each powerinput port to the combined output power, based on the determinedavailable power on each multiple input power port.

By proportionally combining power from electrically isolated power pathsin a remote unit based on the power supplying capability of therespective power supplies, the remote unit can tolerate inaccuracies inthe output power from the power supplies. For example, the type andlength of wires used in the power paths for delivering power to thepower input ports of a remote unit can cause the remote unit to drawpower beyond the limits or regulations of a given power supply. This cansimplify installation procedures for power supplies and remote units ina DAS, because in-field calibrations of power supplies by techniciansbased on variations in power supplies and power paths may be avoided.The remote unit can work with multiple types of power supplies, whichcan have different power delivery capabilities or regulations.

In this regard, FIG. 2 is a schematic diagram of an exemplary remoteunit 200 that can be provided in a DAS. Note that a plurality of theremote units 200 may be provided in a DAS. The remote unit 200 isconfigured to distribute communications services in a DAS 202. Thesecommunications services are provided by power-consuming componentsrepresented by a remote unit load 204 (“load 204”) in FIG. 2. Note thatthe load 204 can represent multiple different loads in the remote unit200. The remote unit 200 is configured to provide an output power 206 tothe load 204 for operations. If the load 204 requires more power tooperate than can be provided by a single power supply over a singlepower wire pair to the remote unit 200, the remote unit 200 can beconfigured to receive input power in multiple input power ports overmultiple respective power paths in the DAS 202. In this regard, theremote unit 200 in FIG. 2 contains multiple input power ports208(1)-208(Q). ‘Q’ signifies that any number of input power ports 208desired can be provided in the remote unit 200. Each input power port208(1)-208(Q) is configured to receive input power 210(1)-210(Q) from arespective power wire pair 212(1)-212(Q) from a respective externalpower path 214(1)-214(Q) in the DAS 202. Multiple power supplies216(1)-216(Q) are provided in the DAS 202 to supply the input power210(1)-210(Q) over the respective power wire pairs 212(1)-212(Q) in theexternal power path 214(1)-214(Q) to the remote unit 200. The powersupplies 216(1)-216(Q) may be located at the remote unit 200 or remotelyfrom the remote unit 200. Each external power path 214(1)-214(Q) iscapable of distributing a given maximum input power 210(1)-210(Q) basedon the respective power supply 216(1)-216(Q) and the power handlingcapability of the respective power wire pair 212(1)-212(Q). In thismanner, the remote unit 200 is configured to receive the input power210(1)-210(Q) from the multiple power supplies 216(1)-216(Q) in case thepower needed to power the load 204 is greater than can be supplied by asingle power supply 216 among the multiple power supplies 216(1)-216(Q).For example, there may be restrictions on the maximum power that can besupplied by a power supply over a power wire pair 212 to the remote unit200.

With continuing reference to FIG. 2, the remote unit 200 includes aplurality of internal power paths 218(1)-218(Q) for routing the receivedinput power 210(1)-210(Q) from the input power ports 208(1)-208(Q) tothe load 204. Each of the internal power paths 218(1)-218(Q) are coupledto a combined power node 220 to provide a combined output power 222 forpowering the load 204. In the remote unit 200 in FIG. 2, an outputfilter 224 is provided to filter the combined output power 222 into theoutput power 206 provided to the load 204.

To avoid differences in the received input power 210(1)-210(Q) on themultiple input power ports 208(1)-208(Q) causing a power supply216(1)-216(Q) from providing higher power than designed or regulated,the input power ports 208(1)-208(Q) in the remote unit 200 areelectrically isolated from each other. In this regard, a plurality ofisolation circuits 226(1)-226(Q) are provided in respective internalpower paths 218(1)-218(Q). For example, the isolation circuits226(1)-226(Q) may be direct current (DC) to DC (DC-DC) converters if theinput power 210(1)-210(Q) is DC input power to provide the output power206 as electrically isolated DC output power. As another example,isolation circuits 226(1)-226(Q) may be alternating current (AC) to DC(AC-DC) converters if the input power 210(1)-210(Q) is AC input power toprovide the output power 206 as electrically isolated DC output power.Each isolation circuit 226(1)-226(Q) is configured to receive therespective input power 210(1)-210(Q) from the respective input powerport 208(1)-208(Q). Each isolation circuit 226(1)-226(Q) is furtherconfigured to provide a respective electrically isolated output power228(1)-228(Q) to the combined power node 220. The electrically isolatedoutput powers 228(1)-228(Q) received at the combined power node 220 arecombined together to form the combined output power 222. The isolationcircuits 226(1)-226(Q) are capable of providing stable electricallyisolated output powers 228(1)-228(Q) to provide a stable combined outputpower 222. Also, by providing the isolation circuits 226(1)-226(Q) inthe respective internal power paths 218(1)-218(Q), the input power210(1)-210(Q) being higher from one or more power supplies 216(1)-216(Q)than other power supplies 216(1)-216(Q) on the return paths230(1)-230(Q) of the respective power wire pairs 212(1)-212(Q) does notcause a greater amount of power to be pulled beyond the power supplycapability limits of a respective power supply 216(1)-216(Q). Optionalinput filters 232(1)-232(Q) can be provided in respective internal powerpaths 218(1)-218(Q) to filter the electrically isolated output powers228(1)-228(Q) before being provided to the combined power node 220.

The load 204 may not require the maximum amount of power that can beprovided in the output power 206 from the contribution of theelectrically isolated output powers 228(1)-228(Q) from the isolationcircuits 226(1)-226(Q) to the combined power node 220. In this regard, aplurality of control circuits 234(1)-234(Q) can be provided in eachinternal power path 218(1)-218(Q), respectively. For example, thecontrol circuits 234(1)-234(Q) may be switching circuits in the form ofswitches. An electronic controller 236 (“controller 236”) is provided inthe remote unit 200 that is configured to control operation of thecontrol circuits 234(1)-234(Q) to control the amount of the electricallyisolated output power 228(1)-228(Q) to be delivered and combined at thecombined power node 220 in the combined output power 222. Asnon-limiting examples, the controller 236 may be a microcontroller,microprocessor, logic circuit, or other control circuit. In this regard,the controller 236 can selectively control the control circuits234(1)-234(Q) to couple the electrically isolated output power228(1)-228(Q) to the combined power node 220 or decouple theelectrically isolated output power 228(1)-228(Q) from the combined powernode 220. To selectively control the control circuits 234(1)-234(Q), thecontroller 236 is configured to provide a control signal 238(1)-238(Q)to each of the respective control circuits 234(1)-234(Q) to control thecontrol circuits 234(1)-234(Q). As an example, the controller 236 canselectively control the control circuits 234(1)-234(Q) to providedifferent levels of combined output power 222 to the load 204 dependingon the power needed by the load 204 for operation. The remote unit 200may also be designed to only need to power certain portions of the load204 based on operation of the remote unit 200.

Capacitor circuits 240(1)-240(Q) may be provided in each of therespective internal power paths 218(1)-218(Q) between the isolationcircuits 226(1)-226(Q) and the control circuits 234(1)-234(Q) to storeenergy from the electrically isolated output power 228(1)-228(Q) tosmooth out or average any power bursts of the electrically isolatedoutput power 228(1)-228(Q). The capacitor circuits 240(1)-240(Q) mayeach be comprised of a single capacitor or network of capacitors.

Note that the isolation circuits 226(1)-226(Q) may have an adjustableoutput power input 237(1)-237(Q), in the form of a current limiter inputor adjustable output voltage that can be set by the controller 236according to adjustment signals 239(1)-239(Q). The adjustment signals239(1)-239(Q) may be either analog or digital signals depending on thetype of isolation circuits 226(1)-226(Q) employed. Using these currentlimiters or output voltage adjustment mechanisms, it is possible tolimit the electrically isolated output power 228(1)-228(Q) deliveredthrough each internal power path 218(1)-218(Q) to the maximum allowedcombined output power 222. In case of voltage based adjustment mechanismfor the isolation circuits 226(1)-226(Q), the current of theelectrically isolated output power 228(1)-228(Q) of a specific isolationcircuit 226 will increase or decrease depending on the voltagedifference between the electrically isolated output power 228(1)-228(Q)of the specific isolation circuit 226 and the combined power node 220,divided by the resistance of the electrical path between these nodes.The series resistance includes both the respective input filter 232 andthe control circuit 234 resistance. In case the resistance between anisolation circuit 226(1)-226(Q) and the combined power node 220 is toolow, an additional series resistor (not shown) may be added to theoutput of the isolation circuits 226(1)-226(Q), to enable fine tuning ofthe output current or voltage of the electrically isolated output power228(1)-228(Q).

FIG. 3 is a flowchart illustrating an exemplary process 300 of theremote unit 200 in FIG. 2 receiving the input power 210(1)-210(Q) frominput power ports 208(1)-208(Q) and selectively controlling the controlcircuits 234(1)-234(Q) to control contribution of each electricallyisolated output power 228(1)-228(Q) to the combined output power 222 atthe combined power node 220. In this regard, remote unit 200 receivesthe input power 210(1)-210(Q) from the external power paths214(1)-214(Q) in the DAS 202 into the input power ports 208(1)-208(Q)each provided in a respective internal power path 218 among a pluralityof internal power paths 218(1)-218(Q) (block 302). The isolationcircuits 226(1)-226(Q) provide the electrically isolated output powers228(1)-228(Q) based on the received input power 210(1)-210(Q) from arespective input power port 208 among the plurality of input power ports208(1)-208(Q) (block 304). The controller 236 selectively controls anamount of the electrically isolated output power 228(1)-228(Q) deliveredin each respective internal power path 218(1)-218(Q), to the combinedpower node 220 into the combined output power 222 to be provided to theload 204 (block 306).

It may also be desired to provide the combined output power 222 in theremote unit 200 in FIG. 2 according to the maximum power supplyingcapabilities of the power supplies 216(1)-216(Q). In this manner, it maybe desired to provide electrically isolated output power 228(1)-228(Q)that is proportional to the power supplying capabilities of the powersupplies 216(1)-216(Q). By proportionally combining electricallyisolated output power 228(1)-228(Q) based on the power supplyingcapability of the respective power supplies 216(1)-216(Q), the remoteunit 200 can tolerate inaccuracies in the output power from the powersupplies 216(1)-216(Q). For example, if three (3) power supplies216(1)-216(3) capable of providing a maximum power of 70, 80, and 90Watts (W) respectively are provided to supply power to the remote unit200, the maximum power available to be provided to the load 204 is 240 W(i.e., 70 W+80 W+90 W). The combined output power 222 can be provided asa proportion of electrically isolated output power 228(1)-228(3) inaccordance with the relative maximum power supplying capabilities of thethree (3) power supplies 216(1)-216(3).

Thus, in this example, as shown in the timing diagram 400 in FIG. 4, thecontrol circuits 234(1)-234(3) could be controlled to be turned on andturned off by the controller 236 to pulse width modulate (PWM) theelectrically isolated output power 228(1)-228(3) in proportion to thepower supplying capabilities of the respective power supplies216(1)-216(3). As shown in FIG. 4, the three (3) electrically isolatedoutput powers 228(1)-228(3) are pulse width modulated (PWM) by thecontroller 236 by controlling respective control circuits 234(1)-234(3).In this example, to PWM the electrically isolated output power228(1)-228(3) in proportion to the power supplying capabilities of therespective power supplies 216(1)-216(3), the combined output power 222at the combined power node 220 of the first electrically isolated outputpower 228(1) is PWM at 29.2% (i.e., 70 W/240 W). This is shown by timeperiod t1 to t2 of period T in FIG. 4. The second electrically isolatedoutput power 228(2) is PWM by the controller 236 at 33.3% (80 W/240 W).This is shown by time period t2 to t3 in period T in FIG. 4. The thirdelectrically isolated output power 228(3) is PWM by the controller 236at 37.5% (90 W/240 W) of time period T. This is shown by time period t3to t4 in period T in FIG. 4.

In this regard, with reference to FIG. 2, the remote unit 200additionally includes optional power measurement circuits 242(1)-242(Q)provided in each internal power path 218(1)-218(Q) to measure the powersupplying capability of the power supplies 216(1)-216(Q) supplying powerto the input power ports 208(1)-208(Q). In this manner, the relativepower supplying capabilities of the power supplies 216(1)-216(Q) can bedetermined by the controller 236, to be able to proportionally controlproviding the electrically isolated output power 228(1)-228(Q) to thecombined power node 220. The power measurement circuits 242(1)-242(Q)are provided between respective input power ports 208(1)-208(Q) and theisolation circuits 226(1)-226(Q) in the remote unit 200. The powermeasurement circuits 242(1)-242(Q) are configured to measure theavailable power provided to the input power ports 208(1)-208(Q) by therespective power supplies 216(1)-216(Q). The power measurement circuits242(1)-242(Q) are further configured to provide the measured availablepower from the input power ports 208(1)-208(Q) to the controller 236.

In this regard, the controller 236 is configured to instruct the powermeasurement circuits 242(1)-242(Q) through control signals 244(1)-244(Q)to measure the available power that can be provided by the powersupplies 216(1)-216(Q) to the respective input power ports208(1)-208(Q). The power measurement circuits 242(1)-242(Q) may beconfigured to measure the maximum available power that can be providedby the power supplies 216(1)-216(Q) to the respective input power ports208(1)-208(Q). As will be discussed in more detail below, the controller236 can use the determined available power that can be provided by thepower supplies 216(1)-216(Q) to selectively control the control circuits234(1)-234(Q) to deliver the electrically isolated output power228(1)-228(Q) to the combined power node 220 based on the availablepower that can be supplied by the respective power supplies216(1)-216(Q). For example, the controller 236 may be configured toselectively control the control circuits 234(1)-234(Q) to proportionallydeliver the electrically isolated output power 228(1)-228(Q) to thecombined power node 220 based on the proportions of available power thatcan be supplied by the respective power supplies 216(1)-216(Q).

In this regard, FIG. 5 illustrates more exemplary detail of an exemplarypower measurement circuit 242 provided in the remote unit 200 in FIG. 2.Only one power measurement circuit 242 is shown for one internal powerpath 218 in the remote unit 200 in FIG. 5 receiving the input power 210from a corresponding power supply 216 for simplicity in illustrationpurposes only. However, it should be noted that a plurality of powermeasurement circuits 242(1)-242(Q) can be provided corresponding to eachinternal power path 218(1)-218(Q), as illustrated in FIG. 2. The powermeasurement circuit 242 is configured to measure the available powerfrom a power supply 216 supplying the input power 210 over the externalpower path 214 to a respective input power port 208. In one example, asdiscussed above, power measurement circuit 242 is configured to measurethe maximum available power from a power supply 216 supplying the inputpower 210 over the external power path 214 to a respective input powerport 208.

With continuing reference to FIG. 5, the power supply 216 iselectrically connected through power wire pair 212 to the remote unit200 to provide the input power 210 to the input power port 208. Thepower wire pair 212 has a resistance represented by resistor (R) 500. Tomeasure the available power of the power supply 216, the input currentI_(IN) of the input power 210 is measured by a current measurementcircuit 502 in the power measurement circuit 242 of the remote unit 200.The input voltage V_(IN) of the input power 210 is measured by a voltagemeasurement circuit 504 in the power measurement circuit 242. In orderto calculate the available input power 210 from the power supply 216,the controller 236 can be configured to manage the measurement of theinput current I_(IN) and the input voltage V_(IN) in the followingexemplary available power measurement process 600 in FIG. 6A discussedbelow.

With reference to FIG. 6A, the available power measurement process 600begins with the controller 236 causing a switch circuit 506 in therespective internal power path 218 to temporarily disconnect the powermeasurement circuit 242 from any load, including a respective isolationcircuit 226 and load 204 (see FIG. 2) (block 602). The controller 236causes the switch circuit 506 to open by providing a switch controlsignal 508 on a switch control line 510 instructing the switch circuit506 to open. Next, the controller 236 causes a first load switch 512coupled to a first load (LOAD A) 514 to close to couple the first load514 to the power supply 216 (block 604). The controller 236 causes thefirst load switch 512 to close by providing a switch control signal 516on a switch control line 518 instructing the first load switch 512 toclose. The controller 236 instructs the current measurement circuit 502to measure the input power 210 on the input power port 208 with thefirst load 514 coupled to the power supply 216 by the first load switch512 being closed (block 606). In this regard, the controller 236provides a current measurement signal 520 on a current measurement line522 to cause the current measurement circuit 502 to measure the inputcurrent I_(IN) while the first load 514 is coupled to the power supply216. The controller 236 also provides a voltage measurement signal 524on a voltage measurement line 526 to cause the voltage measurementcircuit 504 to measure the input voltage V_(IN) while the first load 514is coupled to the power supply 216.

With continuing reference to FIG. 6A, the controller 236 causes a switchcontrol signal 516 on a switch control line 518 to instruct the firstload switch 512 to open (block 608). Next, the controller 236 causes asecond load switch 528 coupled to a second load (LOAD B) 530 to close tocouple the second load 530 to the power supply 216 (block 610). Thecontroller 236 causes the second load switch 528 to close by providing aswitch control signal 532 on a switch control line 534 instructing thesecond load switch 528 to close. The controller 236 instructs thecurrent measurement circuit 502 to measure the input power 210 on theinput power port 208 with the second load 530 coupled to the powersupply 216 by the second load switch 528 being closed (block 612). Inthis regard, the controller 236 provides the current measurement signal520 on the current measurement line 522 to cause the current measurementcircuit 502 to measure the input current I_(IN) while the second load530 is coupled to the power supply 216. The controller 236 also providesthe voltage measurement signal 524 on the voltage measurement line 526to cause the voltage measurement circuit 504 to measure the inputvoltage V_(IN) while the second load 530 is coupled to the power supply216. Based on the measured input current I_(IN) and input voltage V_(IN)for both the first load 514 and the second load 530 being coupled to thepower supply 216, the following equations are created that can be solvedfor maximum available power from the power supply 216 (block 614):V _(PS) =I _(IN-LOAD A) *R _(LINE) +V _(IN-LOAD A), for first load 514(LOAD A)  (1)V _(PS) =I _(IN-LOAD B) *R _(LINE) +V _(IN-LOAD B), for second load 530(LOAD B)  (2)

Once the output voltage (V_(PS)) of power supply 216 and the resistance(R) of power wire pair 212 are known, the maximum input currentI_(IN[Max]) can be calculated by solving equations 1 and 2 above as:I _(IN[Max]) =P _(O[MAX]) /V _(PS),  (3)

-   -   where P_(O [MAX]) is the maximum power allowed to be delivered        by the power supply 216.

Then, the maximum input voltage V_(IN) when the input power port 208reaches the maximum input current I_(IN[Max]) is calculated as:V _(IN [@PS-MAX]) =V _(PS) −I _(IN [Max]) *R _(LINE)  (4)

Thus, the maximum available power P_(IN [MAX]) that can be provided bythe power supply 216 can be calculated as:P _(IN [Max]) =I _(IN [@PS-MAX]) *V _(IN [@PS-MAX])

Thus, using the PWM example above, the duty cycle of each controlcircuit 234(1)-234(Q) in the remote unit 200 in FIG. 2 is defined as theratio between on time and the period time T (see FIG. 4). The duty cycle(DC_(I)) of each control circuit 234(1)-234(Q) can be calculated as:DC _(I) =P _(IN-Q[Max])/(P _(IN LOAD A[Max]) +P _(in LOAD B[Max]) + . .. P _(IN-n[Max]))=P _(IN-Q[Max]) /P _(T Max),

-   -   where ‘Q’ is the number of internal power paths 218(1)-218(Q).

Thus, using the previous PWM example of three (3) power supplies216(1)-216(3) discussed above with reference to FIG. 4, the duty cycleof each control circuit 234(1)-234(3) will be:

-   -   Duty cycle of control circuit 234(1): 70 W/240 W=0.2917.    -   Duty cycle of control circuit 234(2): 80 W/240 W=0.3333.    -   Duty cycle of control circuit 234(3): 90 W/240 W=0.3750.

It should be noted that for applications where the targeted powerconsumption from each of the power wire pairs 212(1)-212(Q) is based ona pre-defined balancing policy (i.e. different power consumption isrequested), solving the above two equations (1) and (2) to get both theoutput voltage V_(PS) and R_(LINE) values is performed. The calculatedoutput voltage V_(PS) will be used in conjunction with the measuredinput current I_(IN) to calculate the power consumption from the powersupplies 216(1)-216(Q). The controller 236 can adjust the powerconsumption from each of the power wire pairs 212(1)-212(Q) to reach thetargeted power consumption for the power supplies 216(1)-216(Q). Thereare two exemplary cases for determining the targeted power consumptionfor the power supplies 216(1)-216(Q):

-   -   in the case that the targeted power consumption includes the        line power drop, the targeted power consumption is        P_(IN)=*V_(IN) for each power supply 216(1)-216(Q); and    -   in the case that the targeted power consumption excludes the        line power drop, the targeted power consumption is        P_(IN)=I_(IN)*V_(IN) for each power supply 216(1)-216(Q).

A given control circuit 234 in the remote unit 200 in FIG. 2 may be openat exactly the same time that the other control circuits 234 are closed.However, a short delay may be inserted between the on states of thecontrol circuit 234(1)-234(Q) for avoiding a situation where two controlcircuits 234 are on at the same time.

When a given control circuit 234 delivers power P_(ON) to the load 204in a duty cycle (DC) portion of the time, the average power consumed atthe input power ports 208(1)-208(Q) of a respective internal power path218(1)-218(Q) is given by:P _(Average) =P _(ON) ×DC _(Q)  (5)

In the maximal case, the average power P_(Average[Max]) that can beconsumed at the input power ports 208(1)-208(Q) of the respectiveinternal power paths 218(1)-218(Q) is limited to P_(IN-Q[Max]) that wascalculated previously:P _(Average[Max]) =P _(IN-Q[Max])  (6)

Substituting equation 5 into equation 6 provides:P _(Average[Max]) =P _(IN-Q[Max]) =P _(ON) ×DC _(Q)  (7)

And therefore, the maximum power that may be delivered to the load 204in the remote unit 200 in each on time is given by:P _(ON[Max]) =P _(IN-Q[Max]) /DC _(Q)  (8)

Since duty cycle (DC_(Q)) is defined as:DC _(Q) =P _(IN-Q[Max]) /P _(T[Max])  (9)

Then, by substituting equation 9 into equation 8, the maximum power thatmay be delivered by the power supply 216(1)-216(Q) for the load 204 ineach on time is found to be:P _(ON[Max]) =P _(IN-Q[Max]) /DC _(Q) =P _(IN-Q[Max]) /P _(IN-Q[Max]) /P_(T [Max]) =P _(T [Max])  (10)

When the load 204 requires exactly the maximum available powerP_(T[Max]), which is P_(T [Max])=240 W in the previous example, then ateach on time of each control circuit 234(1)-234(Q), the input power 210that will be delivered to the load 204 will beP_(ON[Max])=P_(T [Max])=240 W. Input power port 208(1) will deliveraverage power of 70 W and a peak power of 240 W. Input power port 208(2)will deliver average power of 80 W and a peak power of 240 W. Inputpower port 208(3) will deliver average power of 90 W and a peak power of240 W. The capacitor circuits 240(1)-240(Q) in each internal power path218(1)-218(Q) can be used for averaging the power bursts that aresourced by the load 204 from each internal power path 218(1)-218(Q).During the off period, the capacitor circuits 240(1)-240(Q) are chargedwith energy (through the isolation circuits 226(1)-226(Q) of eachinternal power path 218(1)-218(Q)). During off times, the capacitorcircuits 240(1)-240(Q) provide energy to the load 204 in addition to theinput power 210(1)-210(Q) provided to the input power ports208(1)-208(Q). Then, when the consumed power by the remote unit 200 islower the maximum available power P_(T [Max]), the input power210(1)-210(Q) consumed from each input power port 208(1)-208(Q) will beproportionally lower than the maximum power that is allowed to beconsumed through the internal power paths 218(1)-218(Q).

With reference back to FIG. 4, period time T can be determined accordingto the following considerations. When capacitor circuits 240(1)-240(Q)supplement the energy when the respective control circuit 234(1)-234(Q)is on (i.e., connected to the load 204), for on time t_(ON), the voltageon the load 204 (FIG. 2) drops gradually. Assuming that a voltage dropof ΔV is allowed during on time t_(ON), also assume a current of I_(C)is consumed by the capacitor circuits 240(1)-240(Q) during discharge.The above mentioned parameters are related according to the well-knownequation:

$\begin{matrix}{{\Delta\; V} = \frac{I_{C} \cdot t_{on}}{C}} & (11)\end{matrix}$

where ‘C’ is the capacitance of a respective capacitor circuit240(1)-240(Q).

Assuming that three (3) internal power paths 218(1)-218(3) are provided,and therefore t_(ON) is approximately T/3, and assuming that a drop ofΔV is allowed when the control circuit 234 provides 2/3 of the loadcurrent I_(L) during on time t_(ON). Then, based on the above, the lastequation may be re-written as:

$\begin{matrix}{{\Delta\; V} = \frac{{I_{L}\left( {2/3} \right)} \cdot \left( {T/3} \right)}{C}} & (12) \\{T = \frac{\Delta\;{V \cdot C \cdot 9}}{2 \cdot I_{L}}} & (13)\end{matrix}$

Now, assume that a capacitor circuit of 100 μF is used and voltage dropof ΔV=0.05 Volts is allowed when the control circuit 234 provides 2/3 ofthe load current I_(L) during on time t_(ON), and assume that themaximum load current is I_(L)=5 A. Substituting the above assumptions toequation 13 will provide the period duration T.

$T = {\frac{\Delta\;{V \cdot C \cdot 9}}{2 \cdot I_{L}} = {\frac{0.05 \cdot 100 \cdot 10^{- 6} \cdot 9}{2 \cdot 5} = {4.5\mspace{14mu}{\mu Sec}}}}$

In addition to the above analysis, the voltage of electrically isolatedoutput power 228(1)-228(Q) as well as the resistance of the componentson the output side of the respective internal power path 218(1)-218(Q)of the isolation circuits 226(1)-226(Q) may suffer fromtolerance/variation due to limited component accuracy. In order tomitigate this variation, a monitoring process 620 in FIG. 6B may beemployed to determine the duty cycle (DC) of the control circuit234(1)-234(Q) to compensate for the inefficiencies in the isolationcircuits 226(1)-226(Q). In this regard, after the remote unit 200 ispowered on, the controller 236 uses the first load switch 512 to connecta minimum load, such as the first load 514, to a respective internalpower path 218(1)-218(Q) and sets a default or uniform duty cycle of allcontrol circuits 234(1)-234(Q) (block 622). The controller 236 thenperforms the available power supplying capability of the power supplies216(1)-216(Q) according to the example above, and reduces the results tofit the available power to the efficiency of the isolation circuits226(1)-226(Q) (block 624). Next, the controller 236 executes an initialdetermination of the duty cycle of each control circuit 234(1)-234(Q) aspreviously discussed (block 626). The controller 236 then instructs thepower measurement circuits 242(1)-242(Q) to perform current and voltagemeasurements in each internal power path 218(1)-218(Q), as previouslydiscussed (block 628).

With continuing reference to FIG. 6B, the controller 236 determines ifthe fit to power measurement calculations meet expectations for theisolation circuits 226(1)-226(Q) (block 630). If not, the controller 236may optionally correct the duty cycle of the control circuits234(1)-234(Q) to compensate for the isolation circuits 226(1)-226(Q)voltage mismatches on the electrically isolated output powers228(1)-228(Q) due to the actual circuitry intolerances (block 632). Ifcontroller 236 determines that the fit to power measurement calculationsmeet expectations for the isolation circuits 226(1)-226(Q), thecontroller 236 controls the first and second load switches 512, 528 toconnect the first and second loads 514, 530 (or other loads) to therespective internal power paths 218(1)-218(Q), as previously discussed(block 634). The controller 236 then determines if the fit to powermeasurement calculations were to expectations for the isolation circuits226(1)-226(Q) with the first and second loads 514, 530 connected (block636). If not, the controller 236 again optionally corrects the dutycycle of the control circuits 234(1)-234(Q) to compensate for theisolation circuits 226(1)-226(Q) voltage mismatches on the electricallyisolated output powers 228(1)-228(Q) due to the actual circuitryintolerances (block 638). If controller 236 determines that the fit topower measurement calculations meet expectations for the isolationcircuits 226(1)-226(Q), the controller 236 waits a period of time (Tx)to repeat the monitoring process by retuning to block 708 (block 640).

It is also possible to provide a remote unit that can be provided in aDAS, similar to the schematic diagram of FIG. 2 showing an exemplaryremote unit 200 that can be provided in a DAS for combining power fromisolated power paths for powering multiple loads in the remote units indistributed antenna systems (DASs). In this regard, FIG. 7 is aschematic diagram of another exemplary remote unit 200′ that can beprovided in the DAS 202′, wherein the remote unit 200′ is configured tocombine received power from electrically isolated power ports eachreceiving power from respective external power paths, to multiple outputloads for powering the remote unit 200′. The remote unit 200′ is similarto the remote unit 200 in FIG. 2 in that the load 204 is included toreceive an output power 206 based on received power from the powersupplies 216(1)-216(Q) over internal power paths 218(1)-218(Q) thatcoupled to the combined power node 220 to provide a combined outputpower 222 for powering the load 204. In this regard, common elementsbetween the remote unit 200 in FIG. 2 and the remote unit 200′ in FIG. 7are shown with common element numbers in FIGS. 2 and 7, and thus are notnecessary to re-describe. However, the remote unit 200′ also includesadditional input power ports 208′(1)-208′(R) configured to receive powerfrom power supplies 214′(1)-214′(R) to be electrically isolated andcombined for providing power to an additional load 204′.

In this regard, the remote unit 200′ in FIG. 7 contains multiple secondinput power ports 208′(1)-208′(R). ‘R’ signifies that any number ofinput power ports 208′ desired can be provided in the remote unit 200′.Each second input power port 208′(1)-208′(R) is configured to receivesecond input power 210′(1)-210′(R) from a respective second power wirepair 212′(1)-212′(R) from a respective second external power path214′(1)-214′(R) in the DAS 202′. The multiple second power supplies216′(1)-216′(R) are provided in the DAS 202′ to supply the second inputpower 210′(1)-210′(R) over the respective second power wire pairs212′(1)-212′(R) in the second external power path 214′(1)-214′(R) to theremote unit 200′. The second power supplies 216′(1)-216′(R) may belocated at the remote unit 200′ or remotely from the remote unit 200′.Each second external power path 214′(1)-214′(R) is capable ofdistributing a given second maximum input power 210′(1)-210′(R) based onthe respective second power supply 216′(1)-216′(R) and the powerhandling capability of the respective second power wire pair212′(1)-212′(R). In this manner, the remote unit 200′ is configured toreceive the second input power 210′(1)-210′(R) from the multiple secondpower supplies 216′(1)-216′(R) in case the power needed to power thesecond, additional load 204′ is greater than can be supplied by a singlesecond power supply 216′ among the multiple second power supplies216′(1)-216′(R). For example, there may be restrictions on the maximumpower that can be supplied by a power supply over a second power wirepair 212′ to the remote unit 200′.

With continuing reference to FIG. 7, the remote unit 200′ includes aplurality of second internal power paths 218′(1)-218′(R) for routing thereceived second input power 210′(1)-210′(R) from the second input powerports 208′(1)-208′(R) to the second load 204′. Each of the secondinternal power paths 218′(1)-218′(R) are coupled to a second combinedpower node 220′ to provide a second combined output power 222′ forpowering the second load 204′. In the remote unit 200′ in FIG., a secondoutput filter 224′ is provided to filter the second combined outputpower 222′ into the second output power 206′ provided to the second load204′.

To avoid differences in the received second input power 210′(1)-210′(R)on the multiple second input power ports 208′(1)-208′(R) causing asecond power supply 216′(1)-216′(R) from providing higher power thandesigned or regulated, the second input power ports 208′(1)-208′(R) inthe remote unit 200′ are electrically isolated from each other. In thisregard, a plurality of second isolation circuits 226′(1)-226′(R) areprovided in respective internal power paths 218′(1)-218′(R). Forexample, the second isolation circuits 226′(1)-226′(R) may be directcurrent (DC) to DC (DC-DC) converters if the second input power210′(1)-210′(R) is DC input power to provide the second output power206′ as electrically isolated DC output power. As another example,second isolation circuits 226′(1)-226′(R) may be alternating current(AC) to DC (AC-DC) converters if the second input power 210′(1)-210′(R)is AC input power to provide the second output power 206′ aselectrically isolated DC output power. Each second isolation circuit226′(1)-226′(R) is configured to receive the respective second inputpower 210′(1)-210′(R) from the respective second input power port208′(1)-208′(R). Each second isolation circuit 226′(1)-226′(R) isfurther configured to provide a respective second electrically isolatedoutput power 228′(1)-228′(R) to the second combined power node 220′. Thesecond electrically isolated output powers 228′(1)-228′(R) received atthe second combined power node 220′ are combined together to form thesecond combined output power 222′. The second isolation circuits226′(1)-226′(R) are capable of providing stable second electricallyisolated output powers 228′(1)-228′(R) to provide a stable secondcombined output power 222′. Also, by providing the second isolationcircuits 226′(1)-226′(R) in the respective second internal power paths218′(1)-218′(R), the second input power 210′(1)-210′(R) being higherfrom one or more second power supplies 216′(1)-216′(R) than other secondpower supplies 216′(1)-216′(R) on the second return paths230′(1)-230′(R) of the respective second power wire pairs212′(1)-212′(R) does not cause a greater amount of power to be pulledbeyond the power supply capability limits of a respective second powersupply 216′(1)-216′(R). Optional second input filters 232′(1)-232′(R)can be provided in respective second internal power paths218′(1)-218′(R) to filter the second electrically isolated output powers228′(1)-228′(R) before being provided to the second combined power node220′.

The second load 204′ may not require the maximum amount of power thatcan be provided in the second output power 206′ from the contribution ofthe second electrically isolated output powers 228′(1)-228′(R) from thesecond isolation circuits 226′(1)-226′(R) to the second combined powernode 220′. In this regard, a plurality of second control circuits234′(1)-234′(R) can be provided in each second internal power path218′(1)-218′(R), respectively. For example, the second control circuits234′(1)-234′(R) may be switching circuits in the form of switches. Anelectronic controller 236 (“controller 236”) is provided in the remoteunit 200′ that is configured to control operation of the second controlcircuits 234′(1)-234′(R) to control the amount of the secondelectrically isolated output power 228′(1)-228′(R) to be delivered andcombined at the second combined power node 220′ in the second combinedoutput power 222′. As non-limiting examples, the controller 236 may be amicrocontroller, microprocessor, logic circuit, or other controlcircuit. In this regard, the controller 236 can selectively control thesecond control circuits 234′(1)-234′(R) to couple the secondelectrically isolated output power 228′(1)-228′(R) to the secondcombined power node 220′ or decouple the second electrically isolatedoutput power 228′(1)-228′(R) from the second combined power node 220′.To selectively control the second control circuits 234′(1)-234′(R), thecontroller 236 is configured to provide a second control signal238′(1)-238′(R) to each of the respective second control circuits234′(1)-234′(R) to control the control circuits 234′(1)-234′(R). As anexample, the controller 236 can selectively control the control circuits234′(1)-234′(R) to provide different levels of second combined outputpower 222′ to the second load 204′ depending on the power needed by thesecond load 204′ for operation. The remote unit 200′ may also bedesigned to only need to power certain portions of the second load 204′based on operation of the remote unit 200′.

Second capacitor circuits 240′(1)-240′(R) may be provided in each of therespective second internal power paths 218′(1)-218′(R) between thesecond isolation circuits 226′(1)-226′(R) and the second controlcircuits 234′(1)-234′(R) to store energy from the second electricallyisolated output power 228′(1)-228′(R) to smooth out or average any powerbursts of the second electrically isolated output power 228′(1)-228′(R).The second capacitor circuits 240′(1)-240′(R) may each be comprised of asingle capacitor or network of capacitors.

Note that the second isolation circuits 226′(1)-226′(R) may have asecond adjustable output power input 237′(1)-237′(R), in the form of acurrent limiter input or adjustable output voltage that can be set bythe controller 236 according to second adjustment signals239′(1)-239′(R). The second adjustment signals 239′(1)-239′(R) may beeither analog or digital signals depending on the type of secondisolation circuits 226′(1)-226′(R) employed. Using these currentlimiters or output voltage adjustment mechanisms, it is possible tolimit the second electrically isolated output power 228′(1)-228′(R)delivered through each second internal power path 218′(1)-218′(R) to themaximum allowed second combined output power 222′. In case of voltagebased adjustment mechanism for the second isolation circuits226′(1)-226′(R), the current of the second electrically isolated outputpower 228′(1)-228′(R) of a specific second isolation circuit 226′ willincrease or decrease depending on the voltage difference between thesecond electrically isolated output power 228′(1)-228′(R) of thespecific second isolation circuit 226′ and the second combined powernode 220′, divided by the resistance of the electrical path betweenthese nodes. The series resistance includes both the respective secondinput filter 232′ and the control circuit 234′ resistance. In case theresistance between a second isolation circuit 226′(1)-226′(R) and thesecond combined power node 220′ is too low, an additional seriesresistor (not shown) may be added to the output of the second isolationcircuits 226′(1)-226′(R), to enable fine tuning of the output current orvoltage of the second electrically isolated output power228′(1)-228′(R).

Note that each of the processes disclosed herein, including thosediscussed as being performed by the controller 236, can be performed forthe second internal power paths 218′(1)-218′(R) to provide the secondcombined output power 222′ to the second load 204′.

FIG. 8 is a schematic diagram of an exemplary DAS 800 that can includeremote units configured to combine received power from electricallyisolated power ports each receiving power from respective power paths,for powering the remote unit. In this example, the DAS 800 is an opticalfiber-based DAS. The DAS 800 includes optical fiber for distributingcommunications services for multiple frequency bands. The DAS 800 inthis example is comprised of three (3) main components. One or moreradio interfaces provided in the form of radio interface modules (RIMs)802(1)-802(M) are provided in a central unit 804 to receive and processdownlink electrical communications signals 806D(1)-806D(R) prior tooptical conversion into downlink optical communications signals. Thedownlink electrical communications signals 806D(1)-806D(R) may bereceived from a base station (not shown) as an example. The RIMs802(1)-802(M) provide both downlink and uplink interfaces for signalprocessing. The notations “1-R” and “1-M” indicate that any number ofthe referenced component, 1-R and 1-M, respectively, may be provided.The central unit 804 is configured to accept the plurality of RIMs802(1)-802(M) as modular components that can easily be installed andremoved or replaced in the central unit 804. In one example, the centralunit 804 is configured to support up to twelve (12) RIMs 802(1)-802(12).Each RIM 802(1)-802(M) can be designed to support a particular type ofradio source or range of radio sources (i.e., frequencies) to provideflexibility in configuring the central unit 804 and the DAS 800 tosupport the desired radio sources.

For example, one RIM 802 may be configured to support the PersonalCommunication Services (PCS) radio band. Another RIM 802 may beconfigured to support the 800 MHz radio band. In this example, byinclusion of these RIMs 802, the central unit 804 could be configured tosupport and distribute communications signals on both PCS and LTE 700radio bands, as an example. RIMs 802 may be provided in the central unit804 that support any frequency bands desired, including but not limitedto the US Cellular band, Personal Communication Services (PCS) band,Advanced Wireless Services (AWS) band, 700 MHz band, Global System forMobile communications (GSM) 900, GSM 1800, and Universal MobileTelecommunication System (UMTS). The RIMs 802(1)-802(M) may also beprovided in the central unit 804 that support any wireless technologiesdesired, including but not limited to Code Division Multiple Access(CDMA), CDMA200, 1×RTT, Evolution—Data Only (EV-DO), UNITS, High-speedPacket Access (HSPA), GSM, General Packet Radio Services (GPRS),Enhanced Data GSM Environment (EDGE), Time Division Multiple Access(TDMA), Long Term Evolution (LTE), iDEN, and Cellular Digital PacketData (CDPD).

The RIMs 802(1)-802(M) may be provided in the central unit 804 thatsupport any frequencies desired, including but not limited to US FCC andIndustry Canada frequencies (824-849 MHz on uplink and 869-894 MHz ondownlink), US FCC and Industry Canada frequencies (1850-1915 MHz onuplink and 1930-1995 MHz on downlink), US FCC and Industry Canadafrequencies (1710-1755 MHz on uplink and 2110-2155 MHz on downlink), USFCC frequencies (698-716 MHz and 776-787 MHz on uplink and 728-746 MHzon downlink), EU R & TTE frequencies (880-915 MHz on uplink and 925-960MHz on downlink), EU R & TTE frequencies (1710-1785 MHz on uplink and1805-1880 MHz on downlink), EU R & TTE frequencies (1920-1980 MHz onuplink and 2110-2170 MHz on downlink), US FCC frequencies (806-824 MHzon uplink and 851-869 MHz on downlink), US FCC frequencies (896-901 MHzon uplink and 929-941 MHz on downlink), US FCC frequencies (793-805 MHzon uplink and 763-775 MHz on downlink), and US FCC frequencies(2495-2690 MHz on uplink and downlink).

With continuing reference to FIG. 8, the downlink electricalcommunications signals 806D(1)-806D(R) are provided to a plurality ofoptical interfaces provided in the form of optical interface modules(OIMs) 808(1)-808(N) in this embodiment to convert the downlinkelectrical communications signals 806D(1)-806D(R) into downlink opticalcommunications signals 810D(1)-810D(R). The notation “1-N” indicatesthat any number of the referenced component 1-N may be provided. TheOIMs 808 may be configured to provide one or more optical interfacecomponents (OICs) that contain optical to electrical (O/E) andelectrical to optical (E/O) converters, as will be described in moredetail below. The OIMs 808 support the radio bands that can be providedby the RIMs 802, including the examples previously described above.

The OIMs 808(1)-808(N) each include E/O converters to convert thedownlink electrical communications signals 806D(1)-806D(R) into thedownlink optical communications signals 810D(1)-810D(R). The downlinkoptical communications signals 810D(1)-810D(R) are communicated overdownlink optical fiber communications medium 812D to a plurality ofremote units 814(1)-814(S), which may be remote antenna units (“RAUs814(1)-814(S)”). The notation “1-S” indicates that any number of thereferenced component 1-S may be provided. 0/E converters provided in theRAUs 814(1)-814(S) convert the downlink optical communications signals810D(1)-810D(R) back into the downlink electrical communications signals806D(1)-806D(R), which are provided to antennas 816(1)-816(S) in theRAUs 814(1)-814(S) to client devices (not shown) in the reception rangeof the antennas 816(1)-816(S).

E/O converters are also provided in the RAUs 814(1)-814(S) to convertuplink electrical communications signals 818U(1)-818U(S) received fromclient devices (not shown) through the antennas 816(1)-816(S) intouplink optical communications signals 810U(1)-810U(S). The RAUs814(1)-814(S) communicate the uplink optical communications signals810U(1)-810U(S) over an uplink optical fiber communications medium 812Uto the OIMs 808(1)-808(N) in the central unit 804. The OIMs808(1)-808(N) include O/E converters that convert the received uplinkoptical communications signals 810U(1)-810U(S) into uplink electricalcommunications signals 820U(1)-820U(S), which are processed by the RIMs802(1)-802(M) and provided as uplink electrical communications signals820U(1)-820U(S). The central unit 804 may provide the uplink electricalcommunications signals 820U(1)-820U(S) to a base station or othercommunications system.

Note that the downlink optical fiber communications medium 812D anduplink optical fiber communications medium 812U connected to each RAU814(1)-814(S) may be a common optical fiber communications medium,wherein for example, wave division multiplexing (WDM) may be employed toprovide the downlink optical communications signals 810D(1)-810D(R) andthe uplink optical communications signals 810U(1)-810U(S) on the sameoptical fiber communications medium.

The DAS 800 in FIG. 8 that includes one or more RAUs 814 configured tocombine received power from electrically isolated power ports eachreceiving power from respective power paths, for powering the remoteunit, may be provided in an indoor environment. In this regard, FIG. 9is a partially schematic cut-away diagram of a building infrastructure900 employing a DAS 902 that includes one or more remote unitsconfigured to combine received power from electrically isolated powerports each receiving power from respective power paths, for powering theremote unit.

In this regard, the building infrastructure 900 in this example includesa first (ground) floor 904(1), a second floor 904(2), and a third floor904(3). The floors 904(1)-904(3) are serviced by the central unit 906 toprovide the antenna coverage areas 908 in the building infrastructure900. The central unit 906 is communicatively coupled to the base station910 to receive downlink communications signals 912D from the basestation 910. The central unit 906 is communicatively coupled to remoteantenna units 914 to receive uplink communications signals 912U from theremote antenna units 914. The remote antenna units 914 are configured tocombine received power from electrically isolated power ports eachreceiving power from respective power paths, for powering the remoteunit, including according to any of the exemplary examples discussedabove. The downlink and uplink communications signals 912D, 912Ucommunicated between the central unit 906 and the remote antenna units914 are carried over a riser cable 916. The riser cable 916 may berouted through interconnect units (ICUs) 920(1)-920(3) dedicated to eachfloor 904(1)-904(3) that route the downlink and uplink communicationssignals 912D, 912U to the remote antenna units 914 and also providepower to the remote antenna units 914 via array cables 922(1)-922(6).The ICUs 920(1)-920(3) may contain power supplies that supply power overmultiple power paths to the remote antenna units 914. Thus, the arraycables 922(1)-922(6) may each include multiple power conductor pairs toprovide multiple power paths for supplying power to the remote antennaunits 914.

FIG. 10 is a schematic diagram representation of additional detailillustrating a computer system 1000 that could be employed in thecontrollers discussed above, including but not limited to controller 236in the remote unit 200 in FIG. 2. As discussed above, the controller 236is configured to measure the available power from a power supplysupplying power over a power path to a respective input power port inthe remote unit 200, and proportionally control the contribution ofpower from each of the input power ports to the combined output powerbased on the measured available power from the respective powersupplies. In this regard, the computer system 1000 is adapted to executeinstructions from an exemplary computer-readable medium to perform theseand/or any of the functions or processing described herein.

With reference to FIG. 10, the computer system 1000 may include a set ofinstructions that may be executed to predict frequency interference toavoid or reduce interference in a multi-frequency DAS. The computersystem 1000 may be connected (e.g., networked) to other machines in aLAN, an intranet, an extranet, or the Internet. While only a singledevice is illustrated, the term “device” shall also be taken to includeany collection of devices that individually or jointly execute a set (ormultiple sets) of instructions to perform any one or more of themethodologies discussed herein. The computer system 1000 may be acircuit or circuits included in an electronic board card, such as, aprinted circuit board (PCB), a server, a personal computer, a desktopcomputer, a laptop computer, a personal digital assistant (PDA), acomputing pad, a mobile device, or any other device, and may represent,for example, a server or a user's computer.

The exemplary computer system 1000 in this embodiment includes aprocessing circuit (“processor 1002”), a main memory 1004 (e.g.,read-only memory (ROM), flash memory, dynamic random access memory(DRAM), such as synchronous DRAM (SDRAM), etc.), and a static memory1006 (e.g., flash memory, static random access memory (SRAM), etc.),which may communicate with each other via a data bus 1008.Alternatively, the processor 1002 may be connected to the main memory1004 and/or static memory 1006 directly or via some other connectivitybus or connection. The processor 1002 may be a controller. The mainmemory 1004 and static memory 1006 may be any type of memory.

The processor 1002 may be a microprocessor, central processing unit, orthe like. More particularly, the processor 1002 may be a complexinstruction set computing (CISC) microprocessor, a reduced instructionset computing (RISC) microprocessor, a very long instruction word (VLIW)microprocessor, a processor implementing other instruction sets, orother processors implementing a combination of instruction sets. Theprocessor 1002 is configured to execute processing logic in instructionsfor performing the operations and steps discussed herein.

The computer system 1000 may further include a network interface device1010. The computer system 1000 also may or may not include an input1012, configured to receive input and selections to be communicated tothe computer system 1000 when executing instructions. The computersystem 1000 also may or may not include an output 1014, including butnot limited to a display, a video display unit (e.g., a liquid crystaldisplay (LCD) or a cathode ray tube (CRT)), an alphanumeric input device(e.g., a keyboard), and/or a cursor control device (e.g., a mouse).

The computer system 1000 may or may not include a data storage devicethat includes instructions 1016 stored in a computer-readable medium1018. The instructions 1016 may also reside, completely or at leastpartially, within the main memory 1004 and/or within the processor 1002during execution thereof by the computer system 1000, the main memory1004 and the processor 1002 also constituting computer-readable medium.The instructions 1016 may further be transmitted or received over anetwork 1020 via the network interface device 1010.

While the computer-readable medium 1018 is shown in an exemplaryembodiment to be a single medium, the term “computer-readable medium”should be taken to include a single medium or multiple media (e.g., acentralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“computer-readable medium” shall also be taken to include any mediumthat is capable of storing, encoding, or carrying a set of instructionsfor execution by the processing device and that cause the processingdevice to perform any one or more of the methodologies of theembodiments disclosed herein. The term “computer-readable medium” shallaccordingly be taken to include, but not be limited to, solid-statememories, optical medium, and magnetic medium.

The embodiments disclosed herein include various steps. The steps of theembodiments disclosed herein may be formed by hardware components or maybe embodied in machine-executable instructions, which may be used tocause a general-purpose or special-purpose processor programmed with theinstructions to perform the steps. Alternatively, the steps may beperformed by a combination of hardware and software.

The embodiments disclosed herein may be provided as a computer programproduct, or software, that may include a machine-readable medium (orcomputer-readable medium) having stored thereon instructions, which maybe used to program a computer system (or other electronic devices) toperform a process according to the embodiments disclosed herein. Amachine-readable medium includes any mechanism for storing ortransmitting information in a form readable by a machine (e.g., acomputer). For example, a machine-readable medium includes: amachine-readable storage medium (e.g., ROM, random access memory(“RAM”), a magnetic disk storage medium, an optical storage medium,flash memory devices, etc.); and the like.

Unless specifically stated otherwise and as apparent from the previousdiscussion, it is appreciated that throughout the description,discussions utilizing terms such as “processing,” “computing,”“determining,” “displaying,” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data and memories represented asphysical (electronic) quantities within the computer system's registersinto other data similarly represented as physical quantities within thecomputer system memories or registers or other such information storage,transmission, or display devices.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various systems may beused with programs in accordance with the teachings herein, or it mayprove convenient to construct more specialized apparatuses to performthe required method steps. The required structure for a variety of thesesystems will appear from the description above. In addition, theembodiments described herein are not described with reference to anyparticular programming language. It will be appreciated that a varietyof programming languages may be used to implement the teachings of theembodiments as described herein.

Those of skill in the art will further appreciate that the variousillustrative logical blocks, modules, circuits, and algorithms describedin connection with the embodiments disclosed herein may be implementedas electronic hardware, instructions stored in memory or in anothercomputer-readable medium and executed by a processor or other processingdevice, or combinations of both. The components of the distributedantenna systems described herein may be employed in any circuit,hardware component, integrated circuit (IC), or IC chip, as examples.Memory disclosed herein may be any type and size of memory and may beconfigured to store any type of information desired. To clearlyillustrate this interchangeability, various illustrative components,blocks, modules, circuits, and steps have been described above generallyin terms of their functionality. How such functionality is implementeddepends on the particular application, design choices, and/or designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentembodiments.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a processor, a Digital Signal Processor (DSP), anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA), or other programmable logic device, a discrete gateor transistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Furthermore,a controller may be a processor. A processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration).

The embodiments disclosed herein may be embodied in hardware and ininstructions that are stored in hardware, and may reside, for example,in RAM, flash memory, ROM, Electrically Programmable ROM (EPROM),Electrically Erasable Programmable ROM (EEPROM), registers, a hard disk,a removable disk, a CD-ROM, or any other form of computer-readablemedium known in the art. An exemplary storage medium is coupled to theprocessor such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. The processor and the storagemedium may reside in an ASIC. The ASIC may reside in a remote station.In the alternative, the processor and the storage medium may reside asdiscrete components in a remote station, base station, or server.

It is also noted that the operational steps described in any of theexemplary embodiments herein are described to provide examples anddiscussion. The operations described may be performed in numerousdifferent sequences other than the illustrated sequences. Furthermore,operations described in a single operational step may actually beperformed in a number of different steps. Additionally, one or moreoperational steps discussed in the exemplary embodiments may becombined. Those of skill in the art will also understand thatinformation and signals may be represented using any of a variety oftechnologies and techniques. For example, data, instructions, commands,information, signals, bits, symbols, and chips, that may be referencesthroughout the above description, may be represented by voltages,currents, electromagnetic waves, magnetic fields, or particles, opticalfields or particles, or any combination thereof

Unless otherwise expressly stated, it is in no way intended that anymethod set forth herein be construed as requiring that its steps beperformed in a specific order. Accordingly, where a method claim doesnot actually recite an order to be followed by its steps or it is nototherwise specifically stated in the claims or descriptions that thesteps are to be limited to a specific order, it is no way intended thatany particular order be inferred.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit or scope of the invention. Since modifications combinations,sub-combinations and variations of the disclosed embodimentsincorporating the spirit and substance of the invention may occur topersons skilled in the art, the invention should be construed to includeeverything within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. A method of combining power received frommultiple input ports in a remote unit for a wireless communicationsystem, comprising: receiving input power from a plurality of externalpower paths in a wireless communication system into a plurality of inputpower ports each provided in a respective internal power path among aplurality of internal power paths; providing a plurality of electricallyisolated output powers based on the received input power from arespective input power port among the plurality of input power ports;selectively controlling an amount of electrically isolated output powerdelivered in each respective internal power path, to a combined powernode into a combined output power to be provided to at least one remoteunit load, based on the measured available power from the input powerport in the respective internal power path; and measuring availablepower from each input power port among the plurality of input powerports in a respective internal power path among the plurality ofinternal power paths, wherein selectively controlling the amount ofelectrically isolated output power comprises selectively controlling aplurality of switch circuits to selectively couple the electricallyisolated output power in the respective internal power path, to thecombined power node.
 2. The method of claim 1, further comprisingfiltering the electrically isolated output power in each internal powerpath among the plurality of internal power paths.
 3. The method of claim2, wherein the remote unit comprises at least one power measurementcircuit and at least one output filter.
 4. The method of claim 3,wherein the remote unit further comprises an isolation circuit disposedin series between the power measurement circuit and the output filter.5. The method of claim 3, wherein the remote unit comprises at least oneantenna.
 6. A method of combining power received from multiple inputports in a remote unit for a wireless communication system, comprising:receiving input power from a plurality of external power paths in awireless communication system into a plurality of input power ports eachprovided in a respective internal power path among a plurality ofinternal power paths, wherein the remote unit comprises at least oneoptical-to-electrical converter, at least one power measurement circuit,and at least one output filter; providing a plurality of electricallyisolated output powers based on the received input power from arespective input power port among the plurality of input power ports;selectively controlling an amount of electrically isolated output powerdelivered in each respective internal power path, to a combined powernode into a combined output power to be provided to at least one remoteunit load, based on the measured available power from the input powerport in the respective internal power path; measuring available powerfrom each input power port among the plurality of input power ports in arespective internal power path among the plurality of internal powerpaths; and filtering the electrically isolated output power in eachinternal power path among the plurality of internal power paths.
 7. Themethod of claim 6, wherein the remote unit comprises at least oneantenna.
 8. The method of claim 7, wherein the remote unit furthercomprises at least one isolation circuit disposed in series between thepower measurement circuit and the output filter.
 9. A method ofcombining power received from multiple input ports in a remote unit fora wireless communication system, comprising: receiving input power froma plurality of external power paths in a wireless communication systeminto a plurality of input power ports each provided in a respectiveinternal power path among a plurality of internal power paths; providinga plurality of electrically isolated output powers based on the receivedinput power from a respective input power port among the plurality ofinput power ports; and selectively controlling an amount of electricallyisolated output power delivered in each respective internal power path,to a combined power node into a combined output power to be provided toat least one remote unit load, wherein selectively controlling theamount of electrically isolated output power comprises selectivelycontrolling a plurality of switch circuits to selectively couple theelectrically isolated output power from an isolation circuit in therespective internal power path, to the combined power node.
 10. Themethod of claim 9, further comprising measuring available power fromeach input power port among the plurality of input power ports in arespective internal power path among the plurality of internal powerpaths.
 11. The method of claim 10, wherein selectively controlling theamount of electrically isolated output power delivered in eachrespective internal power path is based on the measured available powerfrom the input power port in the respective internal power path.
 12. Themethod of claim 10, further comprising proportionally controlling theamount of electrically isolated output power delivered from therespective internal power path to the combined power node into thecombined output power, based on the measured available power from theinput power port in the respective internal power path.
 13. The methodof claim 10, further comprising filtering the electrically isolatedoutput power in each internal power path among the plurality of internalpower paths.
 14. The method of claim 13, wherein the remote unitcomprises at least one antenna.
 15. The method of claim 14, wherein theremote unit comprises at least one power measurement circuit, at leastone output filter, and an isolation circuit disposed in series betweenthe power measurement circuit and the output filter.
 16. The method ofclaim 9, wherein the remote unit comprises at least one antenna, atleast one optical-to-electrical converter, at least one powermeasurement circuit, at least one output filter, and an isolationcircuit disposed in series between the power measurement circuit and theoutput filter.